Many moons ago, I was in an office adjacent to the flight line. Out of the corner of my eye, I thought I saw something as an aircraft taxied by, but as I wasn’t really looking, was so quick and I wasn’t sure, I let it go.
I later saw the aircraft return and noticed that the front door handle (it was a Sea King) was protruding. It then occurred to me that had someone leant against the door whilst in flight, it could have possibly opened with disastrous consequences. It still haunts me that I said nothing.
From that point on, if I saw or suspected something , I always alerted someone. It doesn’t matter how insignificant, it’s always better to check. I know that some people can feel foolish if it’s found not to be an issue, but foolish trumps remorse any day.